Big Spread Seen in Lung Cancer False Positives

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Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

The rate of benign lung disease that's diagnosed after surgery for suspected lung cancer appears to vary widely from state to state.

Note that 2.1% of patients with a benign diagnosis died in the hospital after lung surgery.

WASHINGTON – Nationwide, one patient in 10 operated on for suspected lung cancer had benign disease, but the false positive rates varied widely from state to state, an analysis showed.

A 2009 snapshot of a cohort of patients showed rates were lowest in Vermont at 1.3% and highest in Hawaii at 25%, according to Stephen Deppen, MS, of Vanderbilt University in Nashville.

Overall, the rate of benign disease was 9.1% and was higher among women than men, Deppen reported here at the annual meeting of the American Association for Cancer Research.

The state-by-state rates form a "patchwork ... with no obvious pattern," Deppen told MedPage Today.

The analysis was prompted by the results of the National Lung Screening Trial, which showed that computed tomography screening reduces lung cancer mortality, leading to calls for widespread screening.

But, Deppen noted, in that study 24% of lung surgeries resulted in a diagnosis of benign disease. Overall, the rate of such a diagnosis is not known, he said, but – if it varied markedly from place to place – it could affect the success of a screening program.

To help fill the gap, Deppen and his colleagues turned to the Medicare Provider Analysis and Review (MedPAR) Hospital National Limited Data Set from 2009.

All told, the data set showed 25,362 patients had surgery for known or suspected lung cancer. Of those, the researchers found, 2,312 (9.1%) had benign disease. The rate among men was 8.5%, compared with 9.8% among women, he said.

The data showed the crude in-hospital mortality rate was 2.3% overall, and was 2.1% for those later diagnosed with benign disease, he said.

The median rate across states was 8.8%, but the variation was significant, Deppen said, with a chi-square P<0.001.

The causes of the differences are not clear, according to Deppen. One possibility is that local practice patterns may affect how rapidly a patient moves from a suspicious result for lung cancer on a chest x-ray to the operating room, he said, and speed may cause errors.

Equally important, chronic fungal infections can lead to imaging results that might cause concern for lung cancer. Deppen points to histoplasmosis as an example, which is common in his home region of Tennessee.

The researchers are currently looking at multiyear data to see if the prevalence of benign disease changes over time. Deppen also said he's looking at geographic information system data to see if the benign-disease rates track with regional prevalences of disease-causing fungi.

"This is important information to know," commented Louis Weiner, MD, of Lombardi Comprehensive Cancer Center at Georgetown University here, who was not involved in the study.

It may that "cultural memories" leading to differences in practice among the medical community are an important influence, Weiner told MedPage Today . But it could also be that there are actual differences in the incidence of benign lung disease from place to place.

The study "gives regulatory agencies, hospitals, and hospital systems tools to drill down and understand how much of this is actual practice variation versus how much is related to an altered prevalence of benign lung disease in different regions," he said.

But, Weiner cautioned, "This is information and information doesn't become powerful until you can convert it into knowledge."

Deppen did not report any external support for the study or make any disclosures.

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